1. Field of The Invention
The present invention relates to a zero insertion force socket having a cover movable with respect to a base thereof, particularly one which has a reinforcement driving mechanism ready for an external tool to move the cover with respect to the base easily.
2. The Prior Art
Zero insertion force (ZIF) sockets are used to connect a CPU to a printed circuit board for years. Normally, this socket needs a relatively long pitch for accommodating a lead-in distance of each contact which allows a corresponding CPU pin to be inserted into the socket with substantially zero insertion force firstly and then moved by a cover of the socket for this lead-in distance to abut against contacting portion of the contact in the socket. These sockets may be referred to U.S. Pat. Nos. 5,489,217 and 5,730,615. For effectively utilizing the space of the socket and lowering the profile thereof a low profile socket has been applied in U.S. application Ser. No. 09/146,998 which is Assigned to the same assignee of the present invention. Referring to FIGS. 7 and 8, the U.S. application Ser. No. 09/146,998 relates to a low profile socket comprising a rectangular cover 4 movably engaged with a rectangular base 5. The cover 4 has opposite sides 41 each of which has two triangular protrusions 45 extending downward and each triangular protrusion 45 forms a blind hole 46 at one wall thereof thereby exposing to an upper surface of the cover 4. The cover 4 has opposite chamfered corners 42 and a virtual diagonal line 43 is defined between the opposite corners 42. A triangular groove 47 is defined substantially along the diagonal line 43 for indicating the movement direction of the cover 4 with respect to the base 5. Two guiding protrusions 44 extend downward from another two opposite corners and each guiding protrusion 44 also defines a blind hole 46 at one wall thereof exposing to the surface of the cover 4. The base 5 has a similar shape and size to the cover 4 in order to mate with the cover 4 when assembled therewith as shown in FIG. 8. The base 5 has two opposite sides 51 each of which has two triangular cutouts 52 for movably receiving the triangular protrusions 45 of the cover 4. Each cutout 52 is defined between two interconnected inner walls and one of the inner walls parallel to a diagonal line (not shown) of the base 5 is called a guiding inner wall 53 which is also parallel to the diagonal line 43 of the cover 4. A tab 53' extends from each guiding inner wall 53 and is slidably received in the blind hole 46 of the triangular protrusion 45 of the cover 4 when the cover 4 is assembled to the base 5. Similarly, the base 5 has another two guiding walls 54 formed in a pair of opposite corners thereof each having a tab 54' projecting therefrom and slidably received in the blind hole 49 defined in the guiding protrusion 44 of the cover 4. The base 5 has two wings 55 extending from another pair of corners and substantially in alignment with the opposite corners 42 of the cover 4 when the cover 4 is assembled to the base 5. The cover 4 defines a plurality of conic holes 48 (only one is shown for simplicity) for receiving corresponding CPU pins (not shown). The base defines corresponding number of passageways 500 (only one is shown for simplicity) each of which is in alignment with a corresponding conic hole 48 and retains a contact (not shown) therein for electrically receiving the CPU pin therein. With this structure, the cover 4 may be moved by a screw driver or the like with respect to the base 5 along the diagonal line 43 thereof.
Although U.S. application Ser. No. 09/146,998 can provide a very low profile socket, the driving mechanism thereof is not satisfactory because an external tool such as a screwdriver when used to drive the cover to move with respect to the base, is apt to slip away out of an operational region defined between a corner of the cover and a vertical wall of an external frame which surrounds the socket. Moreover, the screwdriver is apt to damage the contacting portion (the corner) of the cover or cause warpage of the cover because the cover is too thin to be impacted by the screwdriver. It is requisite to provide a reinforced structure of the socket which can receive impact from a screwdriver without damaging the cover thereof.